X11: Reset dispatching event when nested message loop ends

ui/events/platform/x11/x11_event_source.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/events/platform/x11/x11_event_source.h"
 
 #include <X11/Xatom.h>
 #include <X11/XKBlib.h>
 #include <X11/Xlib.h>
 
@@ skipping 78 matching lines @@
 }
 
 }  // namespace
 
 X11EventSource* X11EventSource::instance_ = nullptr;
 
 X11EventSource::X11EventSource(X11EventSourceDelegate* delegate,
                                XDisplay* display)
     : delegate_(delegate),
       display_(display),
+      dispatching_event_(nullptr),
       dummy_initialized_(false),
       continue_stream_(true) {
   DCHECK(!instance_);
   instance_ = this;
 
   DCHECK(delegate_);
   DCHECK(display_);
   DeviceDataManagerX11::CreateInstance();
   InitializeXkb(display_);
 }
@@ skipping 67 matching lines @@
   XIfEvent(display_, &event, IsPropertyNotifyForTimestamp,
            reinterpret_cast<XPointer>(&dummy_window_));
 
   UMA_HISTOGRAM_CUSTOM_COUNTS(
       "Linux.X11.ServerRTT", (base::TimeTicks::Now() - start).InMicroseconds(),
       1, base::TimeDelta::FromMilliseconds(50).InMicroseconds(), 50);
   return event.xproperty.time;
 }
 
 Time X11EventSource::GetTimestamp() {
-  if (!dispatching_events_.empty()) {
-    DCHECK(dispatching_events_.top());
-    Time timestamp = ExtractTimeFromXEvent(*dispatching_events_.top());
+  if (dispatching_event_) {
+    Time timestamp = ExtractTimeFromXEvent(*dispatching_event_);
     if (timestamp != CurrentTime)
       return timestamp;
   }
   DVLOG(1) << "Making a round trip to get a recent server timestamp.";
   return GetCurrentServerTime();
 }
 
 base::Optional<gfx::Point>
 X11EventSource::GetRootCursorLocationFromCurrentEvent() const {
-  if (dispatching_events_.empty())
+  if (!dispatching_event_)
     return base::nullopt;
 
-  XEvent* event = dispatching_events_.top();
+  XEvent* event = dispatching_event_;
   DCHECK(event);
 
   bool is_xi2_event = event->type == GenericEvent;
   int event_type = is_xi2_event
                        ? reinterpret_cast<XIDeviceEvent*>(event)->evtype
                        : event->type;
 
   bool is_valid_event = false;
   static_assert(XI_ButtonPress == ButtonPress, "");
   static_assert(XI_ButtonRelease == ButtonRelease, "");
@@ skipping 20 matching lines @@
 ////////////////////////////////////////////////////////////////////////////////
 // X11EventSource, protected
 
 void X11EventSource::ExtractCookieDataDispatchEvent(XEvent* xevent) {
   bool have_cookie = false;
   if (xevent->type == GenericEvent &&
       XGetEventData(xevent->xgeneric.display, &xevent->xcookie)) {
     have_cookie = true;
   }
 
-  dispatching_events_.push(xevent);
+  dispatching_event_ = xevent;
 
   delegate_->ProcessXEvent(xevent);
   PostDispatchEvent(xevent);
 
-  dispatching_events_.pop();
+  dispatching_event_ = nullptr;
 
   if (have_cookie)
     XFreeEventData(xevent->xgeneric.display, &xevent->xcookie);
 }
 
 void X11EventSource::PostDispatchEvent(XEvent* xevent) {
   bool should_update_device_list = false;
 
   if (xevent->type == GenericEvent) {
     if (xevent->xgeneric.evtype == XI_HierarchyChanged) {
@@ skipping 40 matching lines @@
 
 void X11EventSource::OnDispatcherListChanged() {
   if (!hotplug_event_handler_) {
     hotplug_event_handler_.reset(new X11HotplugEventHandler());
     // Force the initial device query to have an update list of active devices.
     hotplug_event_handler_->OnHotplugEvent();
   }
 }
 
 }  // namespace ui